Process for preparing fluorocarbon halides

ABSTRACT

FLUOROCARBON HALIDES ARE PREPARED BY REACTING AN UNSATURATED FLUOROCARBON WITH A CYANOGEN HALIDE AND AN IONIZABLE FLUORIDE SALT.

3,770,838 PROCESS FOR PREPARING FLUOROCARBON HALIDES Robert E. A. Dear and Cyril Woolf, Morristown, N.J., assignors to Allied Chemical Corporation, New York,

No Drawing. Filed June 2, 1971, Ser. No. 149,362 Int. Cl. C07c 17/04, 19/08 US. Cl. 260653 4 Claims ABSTRACT OF THE DISCLOSURE Fluorocarbon halides are prepared by reacting an unsaturated fluorocarbon with a cyanogen halide and an ionizable fluoride salt.

In accordance with this invention, fluorocarbon halides having the formula with a cyanogen halide and an ionizable fluoride salt, as

represented by the following equation t?" it R;-o=o-R,' CNX ME R1C'E(IJR1' MoN In similar manner, fluorocarbon halides having the formula are prepared by reacting a perfiuoroalkyne having the formula United States Patent Oflice 3,770,838 Patented Nov. 6, 1973 Suitable ionizable fluoride salts include potassium fluoride, rubidium fluoride, cesium fluoride, silver fluoride and tetra(lower alkyl) ammonium fluoride. Potassium fluoride is preferred.

Suitable aprotic, polar, liquid reaction medium include acetonitrile, dimethylformamide, dimethylsulfoxide, dimethylacetamide, glycol ethers, cyclic polymethylene sulfones, and the like.

The reaction is conveniently carried out at room temperature, but temperatures above or below room temperature, e.g. about --40 C. to about 100 C., can be employed if desired. Similarly, the pressure employed is not critical and can be above or below atmospheric pressure as desired. The reaction is conveniently carried out at pressures autogenously developed at the reaction temperatures employed.

The reactants and products of the process of this invention are all well-known compounds of established utility.

The following examples further illustrate the invention. In each example, the reaction was carried out under substantially anhydrous conditions.

EXAMPLE 1 Eight grams of cyanogen chloride and 19.5 grams of perfluoropropylene were added to 8 grams of potassium fluoride and 80 ml. of acetonitrile at 78 C. After the reaction mixture, which was sealed, had warmed to room temperature, the pressure of the reaction mixture rose to a maximum of 56 p.s.i.g. in about 2 hours and then gradually subsided to a constant pressure of 29 p.s.i.g. The volatile component of the reaction mixture was then bled into a trap maintained at 78 C. and identified as hexafluoroisopropyl chloride. The yield was 13.8 grams.

EXAMPLES 2-9 Following the general procedure of Example 1, perfluoro-Z-butyne and various perfluoroalkenes were reacted with cyanogen chloride or cyanogen bromide and potassium fluoride or silver fluoride in an aprotic, polar liquid reaction medium. In each instance the desired fluorocarbon halide Was obtained in accordance with this invention.

The reactants and reaction media employed in Exam- R EC-R ples 1-9 are tabulated in Table I below.

TABLE I Fluorocarbon Fluoride Cyanogen Example reactant salt halide Medium Product CF CF=CF-. KF ONCl CHaCN CFSCFCICF! CF CF=CF2- KF CNBr CH3CN CFZOFBI'CF: CF3CF=CF KF CNBr Sulfolane 1 CFiCFBrOF; CF CF=CF2 KF CNBr DMF 2 CFaCFBrCF CNBr OH ON OFaCFBIOFs ONO] CHsCN CFaCFGlCF: CNBr DMF CYOIO'CEFQBI CNBr CHsCN Cyelo-CuF Br 9 CFaC COFa KF CNBr Sulfolane CF3OF=OBrCFa 1 Tetramethylenesnlione.

2 Dirnethylionnamide.

with a cyanogen halide and an ionizable fluoride salt in accordance with the following equation X F RfCEC-Rf' CNX N1]? R }=C Rr' MCN The reactions are carried out in an aprotic, polar liquid reaction medium under substantially anhydrous conditions. In the above formulas: X is chlorine, bromine or iodine, preferably chlorine or bromine; R is a perfluoroalkyl radical; R, is fluorine or a perfluoroalkyl radical; and the total number of carbon atoms in R; and R, is from 1 to 12, preferably 1 to 8. Rf and R together can form a cyclic alkyl radical.

The fluorocarbon halideproduct is recovered from the reaction mixture in accordance with conventional methods, such as fractional distillation.

We claim:

1. A process for preparing a fluorocarbon halide having the formula R, being from 1 to 12, which process comprises reacting a perfluoroalkene having the formula wherein R and R are as defined above, with a cyanogen halide having the formula CNX, wherein X is as defined above, and an ionizable fluoride salt selected from the group consisting of potassium fluoride, rubidium fluoride, cesium fluoride, silver fluoride, and tetra(lower alkyl) ammonium fluoride in an aprotic, polar liquid reaction medium under substantially anhydrous conditions.

2. The process of claim 1 wherein the total number of carbon atoms in R and R;' is from 1 to 8.

3. The process of claim 2 wherein the ionizable fluoride salt is potassium fluoride, rubidium fluoride, cesium fluoride, silver fluoride, or tetraflower alkyl) ammonium fluoride.

4. The process of claim 2 wherein X is chlorine or bromine.

DANIEL D. HORWITZ, Primary Examiner U.S. Cl. X.R. 260653 .3 

